Swiss Bank UBS last night replaced chief executive Peter Wuffli with his deputy, Marcel Rohner, and said Mr Wuffli would leave the company.
The surprise change, effective immediately, followed growing calls from UBS critics to bolster results, and perhaps break up the company by getting out of investment banking and focusing on wealth and investment management.
Mr Wuffli (49) had become president of UBS's group executive board in 2001 and took over as CEO in 2003.
Mr Rohner (42) joined the board in 2002 and became Mr Wuffli's deputy in January 2006. Both are Swiss citizens.
UBS also said Marcel Ospel (57) would be nominated for a new three-year term as chairman.
Mr Wuffli's shock departure may fuel speculation that UBS is preparing to alter course strategically after several mishaps, including the surprise closure of a star hedge fund Dillon Reed Capital Management.
UBS, however, downplayed any possible change.